The present invention relates to a control mechanism for controlling the flow of a heat transfer fluid in heat transfer relation serially through a series of heat sources where the fluid flow is directed first through the lower temperature heat sources and finally to the higher temperature heat sources.
The present invention finds particular application in recovery of heat from solar energy receiving cells where multiple cells are set at different angles and attitudes relative to incident sunlight so that the different cells are heated to different temperatures depending upon the position of the sun relative to the cells. For example, the present invention finds application, for example in devices utilizing pyramidal-shaped solar panels where in many instances two panels receive energy from the sun but the angle of incidence is different on the two panels so that the panels are heated to different temperatures.
Without direction for the flow of heat transfer fluid through such pyramidal solar cells, the outlet temperature from the cell is the average of the effective heat transfer temperature of the two cells and therefore maximum temperature heat transfer fluid is not obtained.
In most prior art arrangements utilizing solar heat transfer, flat panels have been utilized where the panels have generally been located on, for example, a southward directed surface in the northern hemisphere and a northern directed surface in the southern hemisphere. In such arrangements the solar rays strike directly on the panel during a small portion of the day. During the majority of the day the solar rays strike the panel at an acute angle so the outlet temperature of the fluid from the panels varies during the day being the maximum at approximately the noon hour solar time, when the sun shines directly on the panel.
In previous arrangements utilizing multiple panels the order of flow through the panels have been fixed so such devices have not been capable of providing the maximum available heat necessary and equally as important maximum temperature in the heat transfer fluid for an extended portion of the day. The outlet temperature from such solar cells is particularly critical when the solar cell is utilized to provide heat to be stored for use at a later time, for example, during the nighttime or when the daytime skies are cloudy or where a maximum temperature is required such as in water distillation.
Prior art arrangements showing attempts to provide maximum solar energy are shown in several references, and the most pertinent known are discussed hereinafter.
U.S. Pat. Nos. 4,121,566; 4,015,584; 4,011,855; and 3,321,012 show various arrangements of fixed parabolic reflectors to receive solar energy and reflect the energy to a collector.
U.S. Pat. Nos. 3,996,917 and 3,884,217 illustrate arrangements which recognize the advantages of maximizing the period of direct incidence of solar radiation on the collector device but accomplish the objectives by mechanical means including a moveable reflector and drive means to cause the reflector to "track" the sun through its path.
Likewise, U.S. Pat. Nos. 4,121,566; 3,986,489; and 4,085,731 show devices which in one way or another operate in response to a change in temperature of a reference either the collector or the liquid utilized for heat transfer.
For example U.S. Pat. No. 4,121,566 teaches an arrangement where multiple parabolic reflectors are utilized and where the heat transfer fluid is withdrawn from a heat source only after it reached a preselected temperature.
Even where solar cells having a geometric design other than a flat plate have been utilized such devices are subject to the movement of the sun and no device is known to provide an arrangement to maximize the outlet temperature from multiple fixed solar heated panels to provide heat for storage or even for other purposes including the provision of fresh water from sea water.